This application claims priority under 35 U.S.C. xc2xa7xc2xa7119 and/or 365 to 9802302-1 filed in Sweden on Jun. 26, 1998; the entire content of which is hereby incorporated by reference.
The invention relates to a method and an arrangement in a cellular radio communications system comprising a plurality of cells. Each cell is assigned a number of channels constituted by timeslots and frequencies and these channels may be configured to be adapted for either voice transmission or data packet transmission in order to obtain spectrum efficiency.
More particularly, the invention relates to systems where subscriber stations in a cell are registered in the system with respect to a location area containing this cell in a manner indicating that they are prepared to perform voice transmission, packet data transmission or both.
Such a system is described in WO, A1, 95/16330, which is referred to herein by reference. This document suggests a system where channels have configurations adapted for voice transmission or packet data transmission. A channel adapted for packet data transmission is arranged to be shared among a number of users in order to take advantage of the bursty nature of packet data services. Such channels may also use more than one timeslot in a transmission frame. The channels may be allocated for voice or packet data use dynamically, depending upon demand of the respective services. The normal state in the system according to this document is that at least one packet data channel is available in each cell. In a described embodiment, however, there may exist cells where packet data channels are available only on demand.
A drawback with systems having at least one packet data channel, henceforth named PDCH, available in each cell is that valuable bandwidth is wasted in cells where packet data communication seldom takes place. Subscribers in the system requesting to perform voice communication might be locked out despite the presence of unused bandwidth. Therefore the system resources are not used effectively.
In systems where PDCHs in a cell are set up only on demand, on the other hand, another disadvantage exists. If PDCH a is set up only on demand, subscribers requesting packet data services will be locked out if all channels are used for voice transmission as traffic channels, henceforth named TCHs. This problem will also affect subscribers already in packet data communication if they migrate into a cell where no PDCH can be set up for the same reason. These subscribers will find their communication shut down. Therefore these systems will be quite unreliable. Reliability is particularly important for packet data services subscribers, since these services are often used professionally and are more sensitive to disturbances.
One object of the present invention is to provide a cellular system for voice and packet data service with improved system resource economy where reliability is maintained.
This object is achieved according to a first aspect of the invention by a method in a system of the initially mentioned kind where a first cell in said system has one PDCH and where said PDCH is currently unused. Briefly, the inventive method includes a first checking procedure to find out whether any subscriber station in said first cell is registered in the system with respect to said first cell in a manner indicating that it is prepared to receive or transmit packet data. If this is not the case, a second checking procedure is carried out to find out if any packet data sessions are performed by any subscriber station in any of the neighbouring cells of said first cell and if not, then said PDCH is reconfigured into a TCH.
The result of this method is that the single PDCH in the cell is reused as a TCH only if the probability that packet data services will be requested in the cell is very low. Thereby system resource economy and/or reliability are improved.
In an embodiment of this method, the first checking procedure is performed to find out if any subscriber station that is registered in the system with respect to any location area containing the cell is prepared to receive or transmit packet data. If this is not the case, then consequently no such subscriber station resides in the cell. The method according to this embodiment is easily integrated with existing cellular systems on the market.
In another embodiment of this method, the second checking procedure is performed only for subscriber stations in neighbouring cells that are non-stationary, resulting in improved efficiency.
According to a second aspect of the invention the above mentioned object of the invention is achieved by a method in a system of the initially mentioned kind, where a first cell in the system has no packet data channel. Briefly, the method consists in awaiting any one of the two following events: a) That a subscriber station is registered in the system with respect to said first cell in a manner indicating that it is prepared to receive or transmit packet data. b) That a packet data session has begun in, or transferred to, any neighbouring cell of the first cell. If any of the events a) or. b) takes place then a TCH is reconfigured into a PDCH.
The result of this method is that a PDCH is established as soon as the probability that packet data services will be requested increases. Thereby system resource economy and/or reliability is improved.
In an embodiment of this method, the event a) occurs if any subscriber station is registered in the system with respect to any location area containing the cell in a manner indicating that it is prepared to receive or transmit packet data. If this is the case, then consequently such a subscriber station possibly resides in the first cell. The method according to this embodiment is easily integrated with existing cellular systems on the market.
In another embodiment of this method, the event b) occurs only with respect to subscriber stations in neighbouring cells that are non-stationary, resulting in improved efficiency.
The first mentioned method is then characterised as it appears from the characterising part of the appended claim 1.
The second mentioned method is then characterised as it appears from the characterising part of the appended claim 4.
An arrangement for carrying out the first mentioned method is characterised as it appears from the characterising part of the appended claim 7.
An arrangement for carrying out the second mentioned method is characterised as it appears from the characterising part of the appended claim 8.